The scanning electron microscope (SEM) has been in widespread use for many years as a general purpose high resolution imaging tool. However, SEMs remain expensive. For example, existing commercial SEMs typically cost at least $100,000. They feature demountable vacuum systems that require vacuum pumping systems that cost $5000 or more. They employ a series of highly stable power supplies for accelerating and focusing the electrons, and complex analog electronics for scanning the electron beam. Many also feature interchangeable apertures, multiple signal extraction modes, multiple electron lenses and cathodes that need replacing or rejuvenating from time to time. All of these characteristic features increase cost. Accordingly, it would be an advance in the art to provide a low cost electron microscope.